1. Field of the Invention
The present invention pertains to a particulate solids processing apparatus or dryer utilizing a hot-pebble or sphere type heat exchange medium which is recycled continuously.
2. Background
There are several instances wherein relatively large quantities of particulate solids such as earth and crushed rock contain or are "contaminated" with volatile fluids such as hydrocarbon compounds both refined and unrefined. These quantities of solids require treatment before they can be returned to the earth or other suitable means of disposal in order to decontaminate or otherwise rid the material of the volatile substances. Various types of drying apparatus have been utilized to decontaminate soils and other materials such as refinery sludges, waste streams and cuttings from drilling operations wherein hot combustion gasses are used in the drying operation to evaporate the volatile fluids. This type of treatment operation results in mixing the volatile fluids with flue gasses and requires substantially large and expensive treatment equipment.
Other problems associated with prior art drying apparatus for solids contaminated with volatile substances pertain to clogging of the drying apparatus with the solids, particularly when the presence of heavy hydrocarbon substances causes the solids to become a relatively sticky and nonflowable residue after evaporation of the more volatile fluids. These and other problems associated with prior art efforts at handling and decontaminating solids, such as earth materials and the like which have been mixed with volatile hydrocarbon fluids, have resulted in relatively complex apparatus. However, in accordance with the present invention, a substantially simplified and unique solids drying or similar treatment device has been developed which includes several advantages as will be set forth hereinbelow.
A related application of the general type of apparatus described herein pertains to extracting oil from shale or oil sands. The present invention is believed to be suitable for such applications and comprises an improvement in prior art apparatus used for retorting oil shale and oil sands.